• Bring a large pot of water to a boil.
• Sauce: Whisk peanut butter with lime juice, soy sauce, honey, chili paste and 2/3 cup hot water in a medium bowl. Set aside.
• Pat tofu dry with a kitchen towel. Toss with cornstarch, salt and pepper until well coated. Heat an extra-large non-stick frying pan over medium-high. Add 1 tsp canola oil, then half of the tofu. Cook, flipping halfway through, until golden brown, 4 to 5 min. Transfer to a plate. Repeat with 1 tsp canola oil and remaining tofu. Transfer to same plate.
• Add remaining 1 tsp canola oil, then mushrooms. Stir-fry until mushrooms start to brown, about 2 min. Add beans and cook until tender-crisp, 3 to 4 min. Remove from heat. Toss with tofu and peanut butter mixture until well coated.
• Cook noodles in pot of boiling water, following package directions but omitting seasoning mix, until tender, 2 to 3 min. Drain and return to pot, then toss with sesame oil.
• Divide noodles among 4 bowls and top with tofu stir-fry, green onions and peanuts. Serve immediately.

Switch It Up: Instead of tofu, use 2 skinless, boneless chicken breasts, halved lengthwise and cut into 1/4-in. slices. Try it with 2 carrots, cut into matchsticks, and 2 zucchini, sliced into half-moons.